This invention relates to a connector for connecting tubing to a component and, more particularly, to such a connector for connecting a section of thin wall tubing to downhole well tools in an oil and gas earth well completion system.
Many connections of the various components making up a well completion system require relative rotation between the various components. For example, when a section of tubing is attached to a well completion tool, matching threads are formed on the tool and the tubing, or to a sub attached to the tubing, so that the connection can be made by advancing and rotating one of the components relative to the other. An example of a connection between reeled tubing and a landing nipple in this manner is disclosed in U.S. Pat. No. 4,669,537, assigned to the assignee of the present invention. However, these type of connections have stress limitations that are well below the stress limitations of a continuous section of reeled tubing.
These type of connections are especially important in connection with downhole tools having a rotary component, such as electrical submersible well pumps which are often used in well completion systems to pump production fluid from a formation, into and through a casing string and a production tubing string, and to a wellhead above surface. Various systems and techniques have been used to install and connect pumps in this environment. For example, the pump is often attached to a production tubing string as shown in U.S. Pat. Nos. 4,502,536 and 4,589,482, or to a mandrel as shown in U.S. Pat. No. 4,749,341. However, in these arrangements, potential leaks occur at the joints between the various sections of the tubing string and the mandrel.
Reeled tubing i.e. continuous, relatively thin-walled, bendable tubing, is becoming more and more popular in downhole servicing of oil and gas wells since it has many advantages when compared to wireline or connected tubing sections. Although reeled tubing would also be ideally suited for well completion systems, since it would eliminate the multiple joints between the above-mentioned tubing string or mandrel sections, it has not enjoyed widespread use in this manner for several reasons. For example, its relatively thin walls preclude threading for attaching the tubing to completion equipment such as pumps, landing nipples, safety values, well hangers, etc. Even if the reeled tubing could be threaded, this would present problems in the field, especially in connection with reeled tubing having relatively large outer diameters. Also, since many existing connectors that connect tubing to associated equipment do not absorb, or transfer, torsional loads they would not be suitable for connecting reeled tubing to a downhole completion component having a rotary member, such as an electrical motor which drives a submersible pump.